Normally a wiper blade of a modern motor vehicle consists of a carrier yoke system with a primary yoke and several clawed yokes, of a rubber wiper strip as well as of reinforcing or resilient rails by way of which the pressure exerted only punctually onto the wiper strip via the claws of the carrier yoke system is distributed over the whole wiper strip as evenly as possible. Thereby the wiper strip has a carrier body comprising a first elongated groove each on both sides, in which elongated grooves these reinforcing rails are located in a depressed way. Furthermore the carrier body of the wiper strip has another elongated groove or an elongated channel each on both sides, into which the ends of the claws of the clawed yokes engage. Wiper blades of such a construction are also especially suitable for cleaning bent windshields of motor vehicles because due to the yoke system and to the movable guiding of the claws in the elongated channel the contour of the wiper lip can be adapted to the windshield to be cleaned, for these claws can be moved in the elongated channel and it has also been taken care that a relative movement is possible between the reinforcing rail and the wiper strip.
Wiper blades of this sort are known, in which the elongated groove for the resilient rail is running to the transverse face of the wiper strip only on one side, whereas on the other side this elongated groove is terminated by a cross web. At a distance of this cross web a securing cam is provided in the elongated groove, which securing cam cooperates with a recess in the reinforcing rail and serves as a securing means against a longitudinal movement of this reinforcing rail in relation to the wiper strip. Thus in this embodiment the reinforcing rail is form-fittingly connected with the wiper strip next to its one end. If such a wiper blade is moved over a bent windshield, the reinforcing rails and the wiper strip are bent respectively, whereby there must be a relative movement between the reinforcing rail and the wiper strip. Due to fixing the reinforcing rail stationarily at the one end more and more of these relative movements inevitably occur at the other end. This also occurs, when unavoidably the wiper strip shrinks because of variations in temperature. Due to fixing the reinforcing rail stationarily at the one end a relatively big relative movement is necessary at the other end. This causes problems especially in case of high wiping speed because the wiper strip is not deformed and adapted quickly enough to the windshield to be cleaned so that the wiping effect is decreased.
Correspondingly these explanations also apply to the way the wiper strip is fixed to the carrier yoke system. As to the known wiper blades the carrier yoke system is fixed at the same end of the wiper strip as the resilient rail and the claw at the other end of the carrier yoke system is relatively moved a lot in relation to the wiper strip, if this wiper strip is moved over a bent windshield.